is, 4 Perkins: The Structure of the Electron 329 
would say that the classical theory applies even within the 
electron, and that even infinitesimal subdivisions of an electron 
may be treated mathematically as charged elements. This view 
necessitates the additional assumption of a binding force or 
influence which keeps the charge within an electron from 
expanding indefinitely. In explaining the mass of an electron 
this method was long ago tentatively accepted, principally 
because a very simple assumption concerning the binding in- 
fluence gives a Lorentz electron (see above) which explains 
exactly the observed mass of /3-ray particles. Nevertheless 
many physicists seem to prefer to use method 2, and say 
that an electron is an indivisible unit whose mass is the same 
as it would be if it were constructed as suggested by method 
1. This is probably because they prefer to think of an 
unchangeable unit of charge 12 rather than a mysterious binding 
influence. This is very satisfactory, if the properties of /3-rays 
are the only facts to be considered, because the necessary 
modification of the classical theory is in this case very simple 
and reasonable. It is perfectly evident, however, 13 that the 
exact form of the necessary modification of the classical theory 
was only arrived at by first considering the problem according 
to method 1. 
As we pass from a consideration of the /3-rays to the problem 
of electrons in the atom, we find that the Lorentz electron fails 
entirely to explain the experimental data. Some of the diffi- 
culties have already been mentioned, and have led to the concep- 
tion of a ring electron. The problem, however, which has 
attracted most attention in this field for the past ten years is 
a certain mysterious discontinuity in the action of electrons in 
the atom. 
It is surprising that nearly all physicists have attacked this 
problem by method 2 instead of testing thoroughly method 
1, which has given perfectly satisfactory results in explaining 
the properties of /3-rays. Besides the fact that the newly 
invented discontinuous force laws and “parcels of energy” are 
directly contrary to the empirical principle of continuity of 
dynamical effects and represent the law of variation with the 
inverse square of the distance as more of a “statistical” coin- 
12 The Lorentz electron is unchangeable as viewed from the standpoint 
of the relativity principle. 
33 Lorentz, H. A., Konink. Akad. Wetensch. Amsterdam, Versl. 12 (1904) 
986; Theory of Electrons, 217. 
